General speaking, for any synth that need more than one skill, the synthesis rate (fail and HQ rate) is calculate on your lower skill(comparing to the respective skill cap). If it need 80 and 50, if you only get "79 and >50" or ">80 and 49" you will be still in the lower tier.

It's not a gil sink to skill goldsmithing in the 50s to get to t2 HQ. You'd have alchemy, skill it up a bit more, then skillup making gold nuggets. Then take the gold nuggets and get to 54 goldsmithing. Get the +1 goldsmithing glasses and you have t2 hq wherever you go.

And before someone says something about panacea, skillup alchemy even more, or find a friend with high enough alchemy and have them make them for you.